This invention relates to lancets for skin prickers, used to draw a drop of blood for analysis.
The conventional construction of such a lancet is a steel needle encased almost entirely in an elongate plastics body but with its sharp tip projecting from one end. The plastics body eases handling and can be shaped to be guided by a compatible firing device and to locate one end of a spring which shoots the lancet forwards when released. It is also quite usual to have the needle tip encased in a twist-off cap integrally moulded with the plastics body. This keeps the tip safe and clean until immediately before use.
One problem with steel needles is that they are generally straight cylindrical bodies, apart from their tips, and they may be siliconised. Therefore the plastics of the body can have very little frictional grip on the needle that it encases, and it is not unknown for the needle to be shifted forwards relative to the body when the cap is twisted and pulled. This results in too deep a prick when the lancet is fired.
The manufacture of such a lancet necessarily involves more than one step. The steel needle has to be made first, and this in itself means taking a blank and then grinding or otherwise sharpening one end to create the tip. Then the needle is located in a mould, and finally is encased in the plastics body. It would clearly be advantageous to reduce the number of operations and form the needle tip with the body. However, an all-steel lancet would be far too extravagant, if nothing else since lancets are disposable, single use items, while simply moulding the body to have a tip at one end of the same material as the plastics body will not produce a sharp enough point if the usual plastics (polyethylene) is employed.
It is the aim of this invention to overcome, at least in part, these drawbacks.